Polynuclear compounds derived from an organic solution

ABSTRACT

Polynuclear compounds dissolved and contained within an organic solvent are separated from the organic solvent by rendering the organic compounds insoluble within the organic solvent. Accordingly this invention removes polynuclear compounds from a saturated organic solvent. The polynuclear compounds are derived from black liquor obtained from kraft digestion. Whereby polynuclear compounds, substantially free of an organic solvent, are obtained from the organic solvent.

BACKGROUND OF THE INVENTION

[0001] Kraft pulping digestion process employs liquor containing sodium hydroxide and sodium sulfide to digest wood chips to produce pulp and remove lignins from wood to create black liquor containing depolymerized, dispersed and dissolved lignins from the wood. Black liquor additionally containing sodium hydroxide and sodium sulfide. Sodium sulfide forms malodorous mercaptons, causing undesired emissions in air. In order to reduce sodium sulfide concentration in “white liquor,” polynuclear compounds can be added to the process to considerably replace sodium sulfide for its intended function, to catalyze removal of lignins from wood. This procedure is described in U.S. Pat. No. 4,012,280. Polynuclear compounds are consumed by combustion and not recycled.

[0002] Accordingly, it is believed that, a method for recovery of polynuclear compounds is without development.

[0003] Therefore, an object of this invention is to obviate many of the limitations and disadvantages of the prior art to digest wood chips and form a black liquor containing polynuclear compounds.

[0004] This invention relates to a method of recycling the organic solvent used to dissolve polynuclear compounds.

[0005] A significant object of this invention is to produce polynuclear compounds from a black liquor.

[0006] Another object of this invention is to utilize an organic solvent to dissolve polynuclear compounds from black liquor.

[0007] An additional object of this invention is to remove polynuclear compounds from the organic solvent.

[0008] Yet another object of this invention is to recycle polynuclear compounds and recycle the organic solvent.

[0009] With the above and other objects in view, this invention relates to the novel features and alternatives and combinations presently described in the brief description of the invention.

PHRASEOLOGY APPLIED IN THE INVENTION

[0010] Wood chips in the presence of white liquor, containing sodium hydroxide at an elevated temperature, will digest wood chips to result in cellulose pulp and form black liquor. White liquor containing sodium sulfide, polynuclear compounds and (or) polysulfide, provide catalysts to delignify wood chips, within a kraft process, and form black liquor. Polynuclear compounds employed as a catalyst, will provide more effectiveness for delignification of wood chips faster than sodium sulfide alone. Addition of antraqinone or equivalent to a kraft process is described on the internet http://www.paperloop.com “Paper Help Online,” pages 1-2, Antraqinone, or equivalent.

[0011] are polynuclear compounds, selected from the group of anthraquinone, 2-methyl-anthraquinone including an individual or a combination thereof Polynuclear compounds from a black liquor are dissolved in an organic solvent to become a solution of polynuclear compounds dissolved in an organic solvent. Polynuclear compounds are separated from the solution to create a saturated organic solvent solution for recycle. This separation method is often performed by cooling the solution to form two phases followed by a centrifuge to separate a phase of polynuclear compounds from a phase of the cooled solution. Both separated phases are recycled to carry out their specific functions. Solubility of anthraquinone is given for several organic solvents at different temperatures indicating that anthraquinone is of limited solubility. This information is presented within Merck Index, eighth edition, pages 88-89. An organic solvent to dissolve polynuclear compounds is usually selected from the group of hydrocarbons, organic halogens and alcohols.

[0012] A centrifuge is employed to separate solids of dissimilar density from that of fluids by generating a force greater than the force of gravity. This implementation is described in Unit Operations, edited by Brown, et al., page 258.

BRIEF DESCRIPTION OF THE INVENTION

[0013] The present invention, in its broadest aspect, is a method to derive polynuclear compounds dissolved in an organic solvent. This invention defines a method to obtain polynuclear compounds, substantially free of the organic solvent used to dissolve the polynuclear compounds. The method comprises: providing an organic solvent containing dissolved polynuclear compounds, and separating the polynuclear compounds from the organic solvent. This method provides recycling of the heretofore separated organic solvent and polynuclear compounds, whereby polynuclear compounds, substantially free of an organic solvent, are obtained from an organic solvent.

[0014] The method, depicted herein, originates from a black liquor containing polynuclear compounds.

[0015] Key features of this invention are:

[0016] Separating polynuclear compounds from an organic solvent containing dissolved polynuclear compounds.

[0017] Polynuclear compounds are derived from a black liquor.

[0018] Polynuclear compounds are employed for delignification of wood chips contained within a kraft digestion setting.

[0019] Polynuclear compounds include antraqinone, or an equivalent.

[0020] Producing polynuclear compounds, substantially free of the organic solvent.

[0021] Recycling the organic solvent to be used to dissolve polynuclear compounds.

[0022] Recycling polynuclear compounds for catalysis and delignification of lignins contained within wood chips.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Features that are considered characteristic of this invention are set forth in the appended claims. This invention, however, both as to its origination and method of operations as well as additional advantages will best be understood from the following description when read in conjunction with the accompanying drawings in which:

[0024]FIG. 1 is a flow sheet denoting the invention as set forth in the appended claims.

[0025]FIG. 2 is a flow sheet denoting a method to create black liquor containing polynuclear compounds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] The flow diagram of FIG. 1 illustrates the preferred embodiment of the present invention. In the diagram, rectangles represent stages or functions of the present invention and not necessarily separate components. Arrows indicate direction of flow of material in the method.

[0027] Referring to FIG. 1, solvent and dissolved polynuclear compounds 10, conveyed to heat exchanger stage 12, and cooled by water 14 to establish phases 16, and heated water 14A. Phases 16, are conveyed to centrifuge 18, to produce polynuclear compounds 20, and solvent saturated by polynuclear compounds 22. Solvent saturated by polynuclear compounds 22, is recycled to dissolve additional polynuclear compounds contained within black liquor obtained from kraft digestion. Centrifuged polynuclear compounds 20, are recycled to act as a catalyst for delignifiction of wood chips provided for kraft digestion. After cooling to provide phases 16, the phases are subjected to a centrifuge 18 to separate the phases by difference in density.

[0028] Referring to FIG. 2, a flow sheet is portrayed denoting a method for kraft digestion of wood chips 30 supplied to a kraft digestion stage 32, to produce pulp 36 and black liquor 38 from white liquor 34 and recycled polynuclear compounds 20 to act as a catalyst for delignification. 

What is claimed is:
 1. A method to derive polynuclear compounds dissolved in an organic solvent, which comprises: providing an organic solvent containing dissolved polynuclear compounds, and separating said polynuclear compounds from said organic solvent, and recycling the heretofore separated organic solvent, whereby polynuclear compounds substantially free of an organic solvent, are obtained from an organic solvent.
 2. The method as described in claim 1 wherein said polynuclear compounds are derived from black liquor obtained from kraft digestion.
 3. The method as described in claim 1 wherein said polynuclear compounds, substantially free of said organic solvent, are subjected to delignification of wood chips within kraft digestion.
 4. The method as described in claim 1 wherein said polynuclear compounds are selected from the group of anthraquinone, 2-methyl-anthraquinone including an individual or a combination thereof.
 5. The method as described in claim 1 wherein said organic solvent is selected from the group of hydrocarbons, organic halogens and alcohols including an individual or a combination thereof.
 6. The method as described in claim 1 wherein said organic solvent containing dissolved polynuclear compounds is subjected to cooling to provide phases of polynuclear compounds and a phase of organic solvent saturated with polynuclear compounds.
 7. The method as described in claim 6 wherein the phases are subjected to a centrifuge to separate phases by differences in density to obtain organic solvent for recycle, and polynuclear compounds substantially devoid of the organic solvent.
 8. The method as described in claim 1 wherein said polynuclear compounds are supplied from kraft pulping digestion.
 9. The method as described in claim 1 wherein said polynuclear compounds are supplied from soda pulping digestion. 